planemo

n. an object in outer space with mass insufficient to achieve fusion but large enough to be made roughly spherical by its own gravity. Subjects: English, Science

Editorial Note: This term and meaning were derived by way of determining what characteristics, exactly, should constitute a planet. Etymological Note: Coined by Gibor Basri from planetary mass object.

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Citations: 2003 Robert Sanders @ University of California, Berkeley UC Berkeley News (Feb. 26) “An orb by any other name”: He proposes a natural upper limit for a “planetary mass object” of about 13 times the mass of Jupiter, or about 4,000 Earths.…Because anything bigger, including stars and brown dwarfs, is able to fuse deuterium, Basri argues that it makes sense to define a “planetary mass object”—or planemo, as he has dubbed them—as an object too small to achieve any fusion. A natural lower limit to the mass of a planemo, Basri says, would be a body large enough for self-gravity to squash it into a round shape. 2003 Jacques Lépine, Jane Gregorio-Hetem Open Issues in Local Star Formation (Dec. 1) p. 266: We find two of our objects to be planemos; though the faintest of our targets, they are much brighter than expected for such low masses. 2006 Alan Boyle Cosmic Log (June 7) “Planet-Sized Problems”: The debate over the definition of planethood has been simmering for years—and it bubbled up again this week, thanks to new research into free-floating planemos, or planetary-mass objects.

Posted 17 Jul 06 | Permalink | Tell a Friend